Vacuum oil purifiers rely primarily on filter elements to remove impurities. These units typically feature two types of filter elements: coarse and fine. The core component of the filtration system is the filter element itself, which consists of a frame, stainless steel wire mesh, and fibrous material; the stainless steel wire mesh is a component prone to wear and requires special protection.
1. Coarse filter elements typically have a filtration rating of 20–50 μm. They are generally made of stainless steel wire mesh, allowing them to be cleaned and reused.
Clogging of the coarse filter element causes the following malfunction in the vacuum oil purifier: severely insufficient oil intake, preventing the purifier from performing normal filtration and circulation.
2. Fine filter elements typically feature a filtration precision of 3–10 μm and utilize high-precision materials, such as glass fiber composites. Due to this high precision, the elements are difficult to clean once clogged. Therefore, maintenance should involve opening the drain valve at the bottom of the fine filter housing to discharge dirty oil after every filtration cycle; this prevents the accumulation of sludge, which would be impossible to remove later.
Clogging of the fine filter element can cause malfunctions in the vacuum oil purifier: pressure within the fine filter housing rises rapidly, potentially damaging the sealing system—particularly the oil pump seals. Such damage leads to oil leakage and prevents the pump from delivering oil while operating under negative pressure. Consequently, meticulous maintenance of the fine filter element is essential.
In fact, an overpressure alarm and protection function can be installed on the fine filter. The system operates by automatically shutting down and triggering an alarm when the pressure rises to 4 MPa. To resume normal operation, the user must drain contaminants and either clean the fine filter housing and element or replace the fine filter element.
The vacuum pump is also a core component of the vacuum oil purifier; therefore, the quality and operational stability of the vacuum pump are fundamental to the unit's overall working efficiency.
Oil leakage is a common issue with vacuum oil purifiers, typically occurring at three locations: the oil sight glass, the oil reservoir gasket, and the motor shaft seals. The primary cause is component aging and seal failure resulting from prolonged use. Leaks at the oil sight glass occur because the glass ages and cracks, or the adhesive bonding it to the reservoir fails, allowing oil to seep out. Regarding the motor shaft, there are both front and rear oil seals; the failure of either one will result in a leak. Additionally, the oil reservoir connects to the motor via an adapter, with a sealing ring at the junction ensuring a tight seal; the aging of this ring can also lead to oil leakage.
Additionally, there is a felt pad on the adapter designed to collect pump oil; if it becomes saturated, the vacuum pump may leak oil. To resolve the leakage, replace the aged oil sight glass, shaft seal, gaskets, and the oil-saturated felt pad. After completing the repairs—and before adding fresh oil—flush the vacuum pump with pump oil.
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